Anchors
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[edit] Intro: Canyoneering Anchors
Anchor building is probably the single greatest expression of creativity and panache in the canyoneering experience. There are myriad ways to secure a rope to tera firma. This is an introduction. Canyoneers are recommended to read many of the excellent rock climbing and mountaineering guides available and to seek professional instruction.
Mountaineers and rock climbers like to build bomb-proof anchors. These are systems that can withstand long falls and great forces. They involve multiple placements positioned to be equalized and redundant. This insures that if one point fails the anchor may still hold. The American Mountain Guide Association recommends following the acronym ERNEST (Equal, Redundant, No Extender, Solid, Timely). Canyoneers should strive to build similar anchors. However, unlike rock climbing, when the cost of failure is often severe injury or death, in the canyons there are times when a less than ideal anchor may suffice. A short rappel into a pool of water may not require bomb-proof establishment. A 60m rappel will. Trusting your life to any anchor requires skill and judgment. Using less than ideal quality is skating on thin ice.
Rich Carlson has proposed an additional acronym to evaluate anchor location: DEAR (Dry, Efficient, Accessible, Retrievable). A canyon anchor needs to be out of the waterway, able to get groups through the rappel station quickly, in a location that is safe to access and that takes the rope pull into consideration. For further information on canyoneering anchors see ACA Forum discussion.
Often canyoneers use a single point to create an anchor. This violates the redundancy rule. When using a single fixed point, such as a tree, consider the quality of the tree and of the webbing. On long rappels consider tying a second piece of webbing or finding a second fixed point adding redundancy to the anchor.
Quality anchor placements require creativity, exploration and tenacity. Often large trees can be located thirty feet up-canyon after a little searching. Consider the security of this placement in favor of sketchy rigs at the lip of a drop.
Forces on an anchor vary depending on the rope and the fall. A dynamic rope stretches, thus applying less impact force on the anchor. A smooth rappel can put little more than body weight on an anchor. In contrast, a sudden bounce on a static line can create forces of up to 1200 lbs. Easy does it on a less than truck anchor.
Not every abandoned anchor is safe. Webbing wears quickly in the wind, sun and sand of the canyon. Old webbing should be replaced if it looks at all frayed or blanched. Old anchors may not represent successful rappels from prior teams. Webbing can be washed downstream and collect in a pile of debris. Each anchor should be carefully inspected and assessed prior to use.
As a matter of etiquette, when leaving an anchor behind consider donating light color webbing that blends with the environment to decrease the general eyesore of the abandoned anchor.
More creative, and often less secure, anchors are covered in advanced anchors.
[edit] Discussion of Webbing
Webbing is what you will use to rig almost all of your anchors. Since it is lightweight, can help save your life, and looks cool when tied in a daisy chain knot and clipped to the outside of your pack - might as well carry a lot of it.
Carry webbing in convenient sizes, but always have a knife handy to cut off any excess.
[edit] Tree Anchor
Trees are often excellent anchors. They can be exceptionally solid and are found in many canyon systems. With good roots and the low torque of a sling at ground level, even small trees may offer a solid anchor. Surprisingly, a number of thick bushes carefully slung together can sometimes get you out of a pinch.
The proper way to rig a rappel when you are using a tree as an anchor is to tie a sling or (webbing) around the tree, with a rap ring on it. The rope passes through the rap ring.
It is important that you do not run a rope directly around a tree. This will injure the tree and may well also injure the rope.
Do not run the rope through a sling by itself. This is not safe because the friction of the rope running through the sling will create a great deal of heat and will likely melt the sling and may damage the rope.
The diagram shown here shows the best way to rig a rappel using a tree as an anchor. One can sling a horn or an arch in a similar manner.
[edit] Slinging a Chock
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Chocks form the center of most anchors. They amount to a wedged object in a small crack or transversing the narrow canyon walls. Chocks can be found or created using wedged logs, rocks or just about any solid debris. Rock climbers have developed a wide array of nuts, hexes and other artificial chocks for fixing anchors into cracks. Unfortunately, the smooth quality of most canyon walls makes these tools of limited use in most canyons and canyoneers typically resort to natural chocks.
There are a few different ways to sling a chock. Here are a couple variations and a brief analysis of each.
- Simple Sling - tie a sling around the chock.
- Advantages
- Simple.
- Uses the least amount of webbing.
- Disadvantages
- Non-redundant. Failure of any strand leads to anchor failure.
- Each webbing strand bears one-half the rope force.
- Need to tie the water knot while setting up the anchor.
- Girth Hitch - tie the chock with a girth hitch.
- Advantages
- Quickly tied. Can use pre-tied or sewn sling.
- Locks the webbing in place – reduces sliding risk.
- Can be used to place rotational force on a chock, keeping it tight in place.
- Disadvantages
- Non-redundant. Failure of any strand leads to anchor failure.
- Each webbing strand bears one-half of the rope force.
- Knot reduces strength of anchor.
- Do not use on living trees. Will harm and possibly kill a living tree by damaging the phloem just inside the bark.
- Simple Sling Doubled Over - throw a sling over the chock and clip the rapide into the two loops.
- Advantages
- Quickly tied. Can use pre-tied or sewn sling.
- Each strand bears one-fourth the rope force.
- Strongest of these four configurations.
- Disadvantages
- Non-redundant. Failure of any strand leads to anchor failure.
- Sling Doubled Over with Overhand Knot Lock - throw a sling over the chock and tie the two loops off with an overhand knot. Clip the rapide into the secured loop.
- Advantages
- Each strand bears one-fourth the rope force.
- Redundancy. Failure of one strand does not lead to anchor failure. However, failure of the single chock still does.
- Disadvantages
- Uses the most webbing.
- Knot decreases the strength of the webbing.
[edit] Bolts
While the placement of new bolts remains controversial, many canyons are already bolted. Outside of natural chocks, bolts are probably the most common canyon anchor system. Even if not placing new bolts, canyoneers should know how to evaluate the quality of a bolted anchor before using it. Further discussion of placement and evaluation can be found on the bolt page.
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[edit] Equalizing Two Anchor Points
When not rappelling off something as solid as a 30 inch oak tree, canyoneers like to use at least two fixed points. In popular canyons the two points are often two bolts.
The weight of the rappel should always be equalized between the fixed points. This can be done either with an self-equalizing loop or a locked equalized loop.
The self-equalizing loop is tied with a half-twist loop.
- Run the anchor webbing through the two anchors.
- Bring down the middle of the webbing and place half a turn in one of the two loops.
- Clip the rapide through the half-loop and the second loop of webbing.
- If one fixed point fails, the rapide is clipped through a loop and remains attached to the webbing.
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- Once set, the rapide should slide to find the lowest point in the system where the two points are equalized.
The locked equalized anchor is tied using an overhand knot.
- The two loops must be equalized so that both sides are tight when placed in the direction of the rappel.
- Bring the loops together and tie a smooth overhand knot.
- Clip the rapide through both loops.
The overhand knot in the locked equalized anchor makes it slightly weaker than the actively equalized anchor. However, when a single fixed point fails the weight of the rappeller is directly transferred to the second fixed point. This makes the weight transfer smoother as there is no short fall when the new slack in the anchor webbing is paid out. This is used commonly when reliability may be an issue; say on two old bolts, where inspection for strength is difficult. The importance of minimizing the shock load, when rappelling on a static line, cannot be underestimated.
The self-equalizing anchor is most commonly used when the strength of multiple anchor points are known to be suspect (say tying into several small trees or a series of knot chocks). Thus, by carefully equalizing the load across each point, the canyoneer hopes to create an anchor that in total is sufficiently secure for a gentle rappel. Use of a locked equalized system in this situation is difficult as small changes in the angle of rappel can shift the weight of the rappeller unduly onto one single anchor point, causing its failure.
A rapide should be avoided in a self-equalizing anchor. It is too narrow for the separate webbing strands to freely slide. One strand inevitably finds itself binding the second strand, thus abrogating much of the self-equalizing effect. Use a larger 'biner or ring if true self-equalization after initiating rappel is needed. One can also set overhand knots part way up each strand of the self-equalizing anchor. This minimizes the shock-load should one point fail but still allows movement in the strands and equalization.
- See ACA discussion.
Ideally the angle between fixed points should be minimized. This places a minimum amount of strain on the two anchor points. The greater the angle, the greater the strain. The percentage of rappel force placed on each of two fixed points can be calculated by the equation: 50% ÷ Cos(Anchor Angle ÷ 2). See table below for examples and forces.
| Anchor Angle | %Rappel Force at Each Fixed Point |
| 0 | 50% |
| 30 | 52% |
| 60 | 58% |
| 90 | 71% |
| 120 | 100% |
| 150 | 193% |
| 170 | 574% |
An unequalized anchor has been dubbed The American Death Triangle. It is not safe as it creates unnecessary strain on the fixed points. It is embarrassing to find. Please properly equalize your anchors.
- See also discussion on Chockstone.org
[edit] Attaching Rope to Anchor
Canyoneers typically use a carabiner. As this gear will generally be abandoned, use of a cheaper rappel ring or rapide is recommended. If you're fresh out of disposable carabineers, use two utility carabiners with the gates placed in opposition. This decreases the risk of failure if one gate opens. If you're down to locking carabiners, well use one of them. If you're totally tapped out of 'biners, it will be an interested drop!
Rather than run the webbing through the rapide or rappel ring it is possible to quickly girth hitch the webbing to the rapide or rap ring. This is done by pulling a loop of webbing through the rap ring and flipping it over the ring. Smooth out the knot and pull it tight before feeding the rope through. This is quick, but like all knots, decreases the strength of the webbing. This also fixes the position of the rap ring on the anchor. Be sure the two sides are equalized before cinching the knot.
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[edit] Position the rapide
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There are two general locations relative to the lip of the canyon where a canyoneer can position the rapide. Each has its own advantage.
- Positioned below the lip: This allows for the easiest rope pull, least injury to the rope and to the rock.
- Positioned above the lip: This allows for the most comfortable rappel start.
The first is preferred for both environmental and safety reasons as it decreases the injury to the rope and the rock. Getting on rappel can be a little tricky. One can shorten the anchor with a Canyon Quickdraw for ease of initiating rappel. All but the last, and most experienced, canyoneer rappel using the shorter anchor. The last canyoneer unclips the quickdraw and then carefully gets on rappel with a belay from below. See extending the anchor and anchor ethics for further discussion.
By pulling the lower rope you can decrease the tendency to pinch the rapide against the rock. This will decrease the friction and wear on the rope.
Figures modified from Mountaineering: Freedom of the Hills, 7th edition, p. 194.
[edit] Don't get the Rope Stuck
There are two general techniques for rope retrieval: the double-strand rappel and the 'biner block. Both work fine. The real trick in getting your rope back is not to get it stuck. This problem is best solved from above, rather than from below. Generally ropes get stuck while falling, however, an anchor far enough back from the lip will require a lot of strength to pull the wet, heavy rope across all that canyon.
- Set the anchor with thoughts of pulling the rope.
- Position the rapide over the canyon lip to avoid pulling the rope over an edge.
- Look for trees, bushes, cracks, ledges, or horns on the way down that might snag the rope.
- Build a new anchor that avoids these obstacles.
- Rappel on a different angle that avoids these obstacles, even if it means getting wet.
- Last rappeller should untwist the rope.
- Before rappelling, test the ability of someone below to pull the rope.
- Once down, pull the rope from a position with the most direct line to the anchor.
- As the end of the rope nears the anchor, pull in smooth, continuous and rapid movements.
If the rope does get stuck, well, hopefully you're not stuck too.
- Breakout the rest of the team's ropes and see if there is enough to get down the canyon.
- Jiggle the rope.
- Jiggle it some more.
- If the rope is stuck in a really, really solid way, you just might, but almost never should, prusik up the rope and try to fix the problem.
- Don't be a fool. Leave the rope. Come back tomorrow and get it.
- Break out the paper and pencil in the first aid kit and leave a note attached to the rope with a phone number. Maybe someone will call.
[edit] Links
- Books
Mountaineering: The Freedom of the Hills
- Web links
Setting anchor slings off two bolts: University of Oregon Rock2
ACA forum Rigging webbing for strength
Anchor Ethics on ACA forum
Anchors Article about anchors in Spanish at Canones y barrancos.
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